Positron emission tomography (PET) has opened the door to in vivo imaging for the purposes of non-invasive disease detection, cancer staging, and drug efficacy screening. The most commonly used PET tracer is 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) due to its relative ease of production, manageable half-life, and ubiquitous application. The increased demand for [18F]FDG has led to the development of a variety of automated radiosynthesizers to lower its cost, enable its production at many different sites, and reduce the radiation exposure of the radiochemist. Automated radiosynthesizers are vital for routine production of PET tracers to minimize radiation exposure to operators and to ensure reproducible synthesis yields.
Though automated synthesis of [18F]FDG is extremely valuable, there are many 18F-labeled PET tracers that await an automated synthesizer to streamline their production. Some of these tracers require high pressures, complicated chemistries, and/or corrosive reagents that make automation very complicated and difficult. For example, nucleoside analogs that have been used in imaging cell proliferation, reporter gene expression, and as possible screening agents for chemotherapy drug efficacy often require high temperature reactions in volatile solvents. Several attempts have been made to automate the syntheses of these tracers on commercially available radiosynthesizers, but have required modifications to the chemistry (e.g. use of alternative solvents or reduced temperatures) to reduce the pressures involved and avoid exceeding the limitations of the radiosynthesizers.
The recent trend in the synthesizer industry towards the use of disposable kits aims to simplify setup and operation for the user, but often introduces several limitations related to temperature and chemical compatibility, thus requiring re-optimization of protocols developed on non-cassette-based systems. Radiochemists would benefit from a single hybrid system that provides tremendous flexibility for development and optimization of reaction conditions while also providing a pathway to simple, cassette-based production of diverse tracers.